Numerical Analysis For The Ultimate Pull-out Capacity Of The Vertically Loaded Anchor Model

The VLA is a new type of drag anchor. Theoretically speaking, in the ideal working state of VLA, the anchor is vertically pressed. But since the VLA usually words on the 1000 to 3000 m deep sea bed, considering the complicated Ocean Condition, like wind, wave and current and also Mooring System, the actual working state of VLA may not be ideal, which means embedment and embedment angle can affect the ultimate pullout capacity for VLA. So the study on the calculations of ultimate pullout capacity for VLA is very important, since most of the VLAs are deeply buried in the deep sea bed. In China, these kinds of studies are mainly carried out using semi-empirical method. There is no such a particular calculating method to fully reflect the ultimate pullout capacity for VLA. Without a big-sized laboratory, it is an effective calculating method to build a numerical model for analysis.The purpose of this article is to present three-dimensional analysis model of ultimate pullout capacity for VLA foundations, accounting for embedment, embedment angle, rate of increase of strength with depth, and width of the foundation. The method of upper bound and limit equilibrium calculations based on assumed mechanisms is used for the ultimate pullout capacity calculation. Finite element analysis of the fluke-soil interaction behaviour of VLA drag anchors in undrained soft clay has allowed calculation of plastic yield loci for characterisation of anchor failure states. The VLA fluke-soil interaction are introduced into the MSC.MARC software .The soil is assumed to be elestic-perfect plastic, with yield determined by the Von Mises condition. On the basis of 2 D model, the paper aims to make an study on the effects of interface and influences of the incremental step .The plastic limit formulation is evaluated through comparisons with finite element simulations and the methed using conventional bearing capacity theory.